He will use them to test a new
technique that could lead to a blood test for humans within months.

Dr Angela Robinson, medical director of the National Blood Service, said she
was encouraged by Dr Soto's work.

"We have been desperately searching for a
diagnostic test that really will work for quite some time now, and this looks
very promising," she said.

"If there is a test that is implementable then obviously we should do it for
the patients' benefit."

Donations fear

Evan Harris MP, a member of the British Medical Association (BMA) Ethics Committee, told Newsnight he was worried about how the test would be applied.

He said: "I can see in a commercial sense that individuals may be offered the test for a price and I would say it's not a good thing for doctors to be involved in that process until it is predicted and something can be done with the information."

Peter Smith, from the Spongiform Encepalopathy Advisory Committee, said the test could have an important public information role.

He said that "one of the prime epidemiological purposes will be to use a test such as this one being developed if indeed they're useful to estimate what size of the population has been infected".

Donor disclosures

Mr Smith expected that individuals going to donate blood "would have to be told that this testing was going to be done".

He added: "I personally would find it very difficult to see a situation where testing was done and it was found positive and individuals were not told that result, even though at this stage we really don't know what we tell them with respect to the prognosis."

Officials at the National Blood Service are now working on a worst case scenario to cope if there is a drop in the amount of blood available.

They stressed that a 50% drop
was the worst they feared and it might be much less.